JEE Main 2023ChemistryChemical EquilibriumHardNumerical

JEE Main 2023 — Chemical Equilibrium Question with Solution

JEE Main 2023 (06 Apr Shift 2)

Question

The equilibrium composition for the reaction 

PCl3+Cl2⇌PCl5 at 298 K is given below:

PCl3eq=0.2 mol L-1, Cl2eq=0.1 mol L-1, PCl5eq=0.40 mol L-1

If 0.2 mol of Cl2 is added at the same temperature, the equilibrium concentrations of PCl5 is _____ ×10–2 mol L–1

Given: Kc for the reaction at 298 K is 20

Enter your answer

Show full solutionCorrect answer: 49
Correct answer
49

Step-by-step explanation

PCl3g0.2+Cl2g0.1⇌PCl5g0.4

Kc=0.40.2×0.1=20

If 0.2 moles of Cl2 is added. When reactant is added the reaction takes place in forward direction.

20=Kc=0.4+X0.3-X0.2-X

⇒0.4+X=200.3-X0.2-X

∴ 0.4+X=200.06+X2-0.5X

0.4+X=1.2+20X2-10X

20X2-11X+0.8=0

X=11±121-6440

=11-7.5540≃0.08625

∴ PCl5=0.48625≃48.625×10-2 or 49×10-2

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About this question

This is a previous-year question from JEE Main 2023, covering the Chemical Equilibrium chapter of Chemistry. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.